India's outsourced call centres are well known, but not its outsourced patients.

By 2010, some estimate there will be two million patients in India on clinical trials.

An entire industry has sprung up, specialising in recruiting patients and managing experiments.

And a BBC investigation into the conduct of these trials has found that some patients are unaware they are being experimented on at all.

Most of the world's largest pharmaceutical companies have a presence in India, but there is concern about how the country achieves its exceptional recruitment rates and questions about fully-informed consent.

Medical language

Six years ago, an experimental drug from the US called M4N was injected into cancer patients in India without being properly tested on animals first.

Later it was discovered that several patients had not known they were part of a clinical trial.

Most of the patients sign on the dotted line without understanding the nature and the consequences of what is being administered to them

Dr Shashank Joshi

One of the doctors who later blew the whistle, Dr V Narayan Bhattathiri, told the BBC: "I can only say that what they did is something unbelievable or incomprehensible.

"I couldn't find any example of such a thing being done, maybe in the last 50 years or so. Maybe something similar could have happened in say concentration camps."

Giving informed consent to be part of an experiment is the golden rule of all clinical trials which goes all the way back to the Nuremberg Code.

But one doctor at the prestigious Lilavati hospital in Mumbai, Dr Shashank Joshi, says the idea of all patients giving informed consent in India is "a myth according to me... because I do not think it's truly informed in the language the patient understands.

"Most of the patients sign on the dotted line without understanding the nature and the consequences of what is being administered to them."

Lack of understanding

Reporter Paul Kenyon tracked down a drug trial being conducted for a major drug company in a psychiatric unit at a hospital in Gujurat.

It was to test an anti-psychotic drug developed by the world's second largest drug pharmaceutical company Johnson and Johnson.

I didn't know that experiments were being carried out on me

Parshottam Parmar

There is already controversy over what is happening, with some doctors levelling the accusation that patients are being taken off their existing medication as part of the trial, with the potential they could suffer unnecessarily .

Dr Vikram Patel from the British Journal of Psychiatry says: "The most obvious problem is that they won't get better or they will continue to suffer this extremely severe psychiatric illness, much longer than they need to."

But the ethical concerns go deeper when Kenyon finds a patient who took part in the trial.

"I was just told that the drugs were American. They used to give me the tablets and I used to eat them," says Parshottam Parmar.

"We just sign because I believe the doctor takes the signature to help us. That's why I sign it."

He says he had no idea that he was part of a clinical trial.

"I didn't know that experiments were being carried out on me. I was told that the old drugs were discontinued and were no longer available in the pharmacies.

"I don't know a lot about all these things. I am poor and I live in a small hut and I don't understand many things. The doctors are intelligent. They write the drugs for me so I have to take them accordingly."

Johnson and Johnson's spokesman Dr Vivek Kusumaker told us: "We have looked at this particular trial and we've got consent from the patient or from a relative in every case.

"If there is any instance brought to our attention that something was not OK we will take that seriously. We have said that we shut down sites if we don't think we are carrying out research to the highest code of ethics in which we believe."

Drug Trials: The Dark Side was broadcast on Thursday, 27 April, 2006 at 2100 BST on BBC Two.